As can be appreciated by those of skill in the art of orthopaedic apparatuses and methods, it is common to utilize a bone fusion plate for attaching to bones at a desired location to position the bones relative to one another wherein bones beneath the plate can be fused together. To accomplish such bone fusion, bone plates which have commonly been used to date are typically flat along a single plane and include holes for attachment of bone fasteners, such as bone screws, to bones below. This type of attachment of a bone plate to the bones below typically provides vertical compression only between the bones and the bone plate above and does not provide for any kind of radial or lateral compression which can urge the bones toward one another and which is highly advantageous in bone fusion.
Bone plates suffering the above-mentioned disadvantages exist in a variety of configurations and can be adapted for use at various anatomical locations, such as, for example, with wrist bones, foot bones, cranial-facial bones, and bones at any other location suitable for bone fusion. For use specifically with wrists, it is common for a wrist fusion apparatus such as a wrist fusion plate to be used in arthrodesis to fuse bones of the wrist area of a patient in a desired orientation. A variety of configurations and designs of fusion plates specifically for use with wrists exist within the prior art for utilization in this manner.
Generally, the use of a dorsal wrist fusion plate is indicated in patients with osteoarthritis or post-traumatic wrist arthritis, conditions involving significant loss of bone substance, and failed partial or limited wrist arthrodesis. Wrist arthrodesis can also be successfully utilized in patients with carpal instability. A fusion plate can be utilized in patients with rheumatoid arthritis, although simpler stabilization techniques are currently fairly predictable. Contraindications to utilizing a wrist fusion plate adapted for fusion in a limited manner as recognized by those of skill in the art include any concomitant disease or deficiency which may compromise the function of the plate.
Some types of wrist fusion apparatuses attach to the radius and extend from there to a metacarpal, such as the third metacarpal, of the hand for utilization in wrist fusion. Wrist fusion apparatuses of this variety are typically fastened both to the radius and to the third metacarpal by bone screws, and wrist fusion apparatuses of this variety also therefore overlie the carpus area and the bones of the carpus area which are positioned between the radius and the metacarpal bones. As known to those of skill in the art, bone grafts can be packed between the radius, the carpus area bones, and the metacarpals after such a wrist fusion plate is in place, and the bone grafts typically will bond with the adjacent bones in order to create a fused bone mass at the wrist joint.
U.S. Pat. No. 5,853,413 to Carter et al. discloses such a wrist fusion apparatus in the form of a plate configured to extend over the carpus area and to position at least one metacarpal relative to the radius. A saddle portion is included in the wrist fusion plate and is placed over the carpus area. A proximal end extends from the saddle portion and is attachable to the radius, while a distal end extends from the saddle portion and is attachable to one of the metacarpals. The proximal end extending from the saddle portion defines a first longitudinal axis, and the distal end extending from the saddle portion defines a second longitudinal axis wherein the first and second longitudinal axes are not actually aligned in a medial-lateral direction.
Wrist fusion plate apparatuses and methods such as that disclosed in Carter et al. require attachment of a portion of the wrist fusion plate to one or more of the metacarpals of the hand as well as to the radius. The resulting bone fusion can be referred to as total wrist fusion and will typically render a person with no ability to flex the subject wrist for abduction or adduction because of the total fusion of the carpal area bones with the radius and one or more metacarpals. In some circumstances, therefore, it can be desirable to fuse bones of the carpus area only without causing fusion to either the radius or to a metacarpal. In such circumstances, the resulting fusion can be referred to as partial or limited wrist fusion as compared to the total wrist fusion created when the radius and a metacarpal are also fused with the carpal bones.
Regardless of whether a bone fusion apparatus for wrist bone fusion or for fusion of other area bones, and regardless of whether a bone fusion apparatus is adapted for limited wrist fusion or for total wrist fusion, slippage or sliding of the bone fusion apparatus is a common problem which can often be encountered during the affixation or fastening of a bone fusion apparatus, especially for affixation of bone fusion apparatuses for limited, wrist bone fusion. As can be readily appreciated by those of skill in the art, the procedure of screwing in the bone screws which are typically used as fasteners for bone fusion apparatuses can be quite difficult to accomplish without some undesirable movement of the bone fusion apparatus itself. Such movement therefore can make it very difficult to precisely position and affix bone fusion apparatuses.
Despite the prior art bone fusion apparatuses and methods, there remains much room for improvement in the art, particularly for a bone fusion apparatus and method which can be used for fusing a variety of bones in a variety of different anatomical locations.